In such a case that an image of a television broadcasting signal received by a tuner is displayed on a display unit separately provided from this tuner, and also this tuner cannot be connected to the display unit, image signals are transmitted from the tuner to the display unit by utilizing electromagnetic waves and infrared rays. In such a case, when an interference object passes through a space between a transmitting position (tuner) and a receiving position (display unit), or interference electromagnetic waves are produced near the tuner and display unit, the following phenomenon will occur. That is, the infrared-ray or electromagnetic wave reception conditions would be deteriorated. In particular, when a signal is received by a moving object while the moving object is traveling through towns and mountainous areas, since signal reception conditions are varied in accordance with the peripheral environments, such a poor reception condition would occur.
Conventionally, even when the signal reception conditions are deteriorated, the demodulating process operation is carried out in a similar manner executed under better signal reception conditions. Thus, the demodulated voice (audio) and pictures are directly outputted.
However, when the signal reception conditions are deteriorated, if the demodulated signal is directly outputted, then the voice and pictures are disturbed. If the voice is disturbed within a certain allowable range, then this disturbed voice does not give such a strong unpleasant feeling. To the contrary, since the picture disturbance is easily sensible, there is such a problem that if the deteriorated signal reception conditions cause even a small amount of a poor picture to be displayed, then this poor picture may give unpleasant feelings to users.